Apparatus

ABSTRACT

The present disclosure relates to an apparatus having an evaporator with a base plate having a first surface for receiving a heat load from one or more electric components, tubes that partly penetrate into the base plate via a second surface of the base plate for providing evaporator channels which are embedded into the base plate and condenser channels which are located outside of the base plate. In order to obtain a compact and efficient apparatus, the connecting parts can include hollow sections located within the tubes, each hollow section connecting the channels of a tube to each other in a vicinity of an end of the tube in order to allow fluid to flow between the channels of the tube via the hollow section.

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to European PatentApplication No. 1 3170378.7 filed in Europe on Jun. 4, 2013, the entirecontent of which is hereby incorporated by reference in its entirety.

FIELD

This disclosure relates to an apparatus with an evaporator for receivinga heat load from one or more electric components in order to provideadequate cooling for the components.

BACKGROUND INFORMATION

Closed electric cabinets, such as cabinets containing drives controllingthe operation of electric motors, can employ cooling devices forensuring that heat generated by the electric components do not raise thetemperature inside the cabinets to a level where damage may occur.

These known cooling devices can include heat sinks or heat exchangersreceiving heat loads from the electric components, and via which acooling air flow passes for dissipating the heat load to the surroundingenvironment. Such known cooling devices can include metal pieces withoutany kind of fluid circulation, or of devices with fluid circulation andwhich employ a pump for generating the fluid circulation.

There also exists more efficient apparatuses for cooling electriccomponents, such as thermosyphons, capable of circulating a coolingfluid without a need for a pump. It would be desirable to utilize suchapparatuses in older electric cabinets which have originally beenmanufactured to include known heat sinks or heat exchangers.

Such more efficient apparatuses, however, can have shape and dimensionsin question. Due to the shape and dimensions these more efficient knownapparatuses cannot be utilized to the extent otherwise possible.

SUMMARY

An apparatus is disclosed comprising: an evaporator with a first surfacefor receiving a heat load from one or more electric components; tubeshaving internal longitudinal walls dividing the tubes into channels,wherein the tubes partly penetrate into the evaporator for providingevaporator channels which are embedded into the evaporator; andcondenser channels which are located outside of the evaporator:connecting parts at first and second ends of the tubes for passing fluidfrom the evaporator channels into the condenser channels and for passingfluid from the condenser channels into the evaporator channels, theconnecting parts having hollow sections located within the tubes, eachhollow section connecting the channels of a tube to each other in avicinity of an end of the tube in order to allow fluid to flow betweenthe channels of the tube via the hollow section; and fins extendingbetween the condenser channels of adjacent tubes.

BRIEF DESCRIPTION OF DRAWINGS

In the following, embodiments of the present invention will be describedin closer detail by way of example and with reference to the attacheddrawings, in which:

FIG. 1 illustrates a working principle of an exemplary apparatusdisclosed herein;

FIGS. 2 to 4 illustrate an exemplary apparatus disclosed herein;

FIGS. 5 to 8 illustrate a second exemplary embodiment of an apparatus asdisclosed herein; and

FIGS. 9 and 10 illustrate alternative exemplary tube designs.

DETAILED DESCRIPTION

The present disclosure provides an apparatus where the shape anddimensions of the apparatus can place less restrictions on installationswhere the apparatus can be utilized.

The use of connecting parts including hollow sections located within thetubes, which hollow sections connect the channels of a tube to eachother in the vicinity of an end of the tube, makes it possible to obtainefficient circulation between evaporator channels and condenser channelswithout a need for a large fluid distribution element at the ends of thetubes. Therefore the shape and dimensions of the apparatus may beselected more freely than previously.

The FIG. 1 apparatus 1 includes an evaporator 2 including a base platefor receiving a heat load 3 from one or more electric components. Theelectric components may be directly attached to the evaporator ofaluminum, for instance.

One or more tubes 4 with internal longitudinal walls 5 penetrate partlyinto the second surface 22 of the evaporator 2 such that at least onechannel of the penetrating tubes can be embedded in the base plate 2 toform an evaporator channel 6. Fluid located in this evaporator channel 6(or evaporator channels 6) receives the heat load 3 via the base plate.Due to temperature rise and evaporation, the fluid will flow upwards inthe evaporator channel 6 in the illustrated example.

A hollow section 8 within each tube 4, in other words an end section ofthe tube where no internal walls are present, connects the channels 6and 7 of each tube to each other in a first end 10 of the tubes 4 inorder to allow fluid to flow between the channels 6 and 7 of the tubes4.

The channels located outside the evaporator 2 are condenser channels 7.The fluid which has entered the condenser channels 7 will be cooledwhile moving towards the second end 11 of the tubes 4. The cooling maybe accomplished by transfer of heat from the fluid through the walls ofthe condenser channels 7 to the surrounding air.

A hollow section 9 within each tube 4, in other words an end section ofthe tube where no internal walls are present, connects the channels 7and 6 of each tube to each other in the second end 11 of the tubes 4 inorder to allow fluid to flow between the channels 7 and 6 of the tubes4. Consequently, the cooled fluid is returned from the condenserchannels 7 to the evaporator channels 6 for a new cycle. In practice,the returning fluid has condensed into a liquid state.

In the illustrated position the fluid circulation occurs without a pumpdue to gravity, the temperature differences and the density differencesof the fluid (liquid/vapour) in different parts of the apparatus. Inorder to ensure efficient circulation of the fluid and to ensure thatadequate circulation occurs also when the apparatus is in anotherposition (such as in the horizontal position of FIGS. 2 to 4) than inthe illustrated upright position, some of the channels 6 or 7 of thetube 4 may have capillary dimensions. In that case, if the condenserchannels 7 returning fluid from the first end 10 of the apparatus to thesecond end 11 of the apparatus have capillary dimensions, a flow offluid from the first end 10 to the second end 11 may take place alsowhen the apparatus is in another position than the upright positionillustrated in FIG. 1. In this context “capillary dimensions” refers tochannels that are capillary sized, in which case they have a size smallenough so that bubbles can grow uniquely in a longitudinal direction (inother words in the flow direction as opposed to the radial direction)and thereby create a pulsating effect (bubble pumping or bubble lifteffect) by pushing the liquid. In this example they are capillary sizedso that no additional capillary structures are needed on their internalwalls. The diameter of a channel which is considered capillary dependson the fluid that is used (boiling) inside.

The following formula, for example, can be used to evaluate a suitablediameter:

D=(sigma/(g*(rhol−rhov)))̂0.5,

where sigma is the surface tension, g the acceleration of gravity, rhovthe vapor density and rhol the liquid density. This formula givesexemplary values from 1 to 3 mm for R134a (Tetrafluoroethane), R145faand R1234ze (Tetrafluoropropene), which are exemplary fluids suitablefor use in the apparatus illustrated in the Figures.

FIGS. 2 to 4 illustrate an apparatus. The working principle andconstruction of the apparatus explained in FIGS. 2 to 4 are similar tothe one explained in connection with FIG. 1, unless otherwise pointedout in the following explanation.

FIG. 2 illustrates the entire apparatus, FIG. 3 is a partial front viewof one tube 4 and the base plate 2, and FIG. 4 illustrates a crosssection of the tube 4 and base plate 2 along line A-A in FIG. 2. Theillustrated apparatus may be installed in a motor drive, such as in afrequency converter utilized for controlling feed of electricity to anelectrical motor.

FIG. 2 illustrates, by way of example, that the apparatus 21 includes 16tubes 4 arranged in parallel to partly penetrate into the base plate ofthe evaporator 2 via a second surface 22 of the evaporator 2. As bestseen in FIG. 3, at least two channels (illustrated by dotted lines) ofthe tubes are thereby embedded into the evaporator 2. These embeddedchannels work as evaporation channels 6, receiving a heat load from oneor more electric components 23 attached to a first surface 24 of thebase plate 2. The remaining channels located outside of the evaporator 2work as condenser channels 7 which transfer heat from the fluid into air25 flowing between the condenser channels 7. In order to enhance thetransfer of heat into the air 25, fins 26 can, for example, be arrangedto extend between the condenser channels 7 of adjacent tubes 4, asillustrated in FIG. 2.

FIG. 4 illustrates an exemplary fluid flow in more detail. The number ofchannels and the dimensions of the channels and the other elements may,in practice, vary significantly from what is illustrated in FIG. 4. Thehollow sections 8 and 9 at the first 10 and second 11 ends of the tubeswork as connecting parts allowing fluid to pass between the evaporatorchannels 6 and the condenser channels 7 without a need for providing thetubes or the apparatus with external fluid distribution elements outsidethe tubes 4 for this purpose. This makes it possible to obtain a compactand efficient apparatus. Naturally, in some embodiments it is possibleto have a hollow section 8 or 9 in only one end of the tubes and atraditional external fluid distribution element in the other end of thetubes, as an extension of the tubes, for instance.

In order to ensure an even distribution of fluid within the entireapparatus, the apparatus 21 illustrated in FIGS. 2 to 4 can be providedwith a manifold 27 extending through adjacent side walls of the tubes 4.The manifold 27 interconnects at least one channel of each tube 4 witheach other and allows fluid to flow between all tubes. To arrange themanifold in this way has the advantage that the manifold does notrequire any additional space outside the ends of the tubes 4, forinstance. Advantageously, the manifold 27 can include a hole extendingthrough the base plate of the evaporator 2 and the parts of the tubes 4(evaporator channels 6) which penetrate into the evaporator 2, asillustrated in FIGS. 2 to 4. In this way the need for using separatetubes that need to be attached to the holes in the tubes andadditionally sealed against leakage at each such hole can be avoided.

In FIG. 2 it is assumed by way of example, that the end of the hole(bore) which works as the manifold 27 is plugged with a suitable plug28. However, in order to add or remove fluid to the channels of theapparatus 21 an additional filling valve 29 provides access to one ormore of the channels of the tubes 4 and/or the manifold 27. Depending onthe implementation and the available space, the filling valve 29 maynaturally work as the plug that plugs the end of the manifold 27, inwhich case it is located where the plug 28 is illustrated in FIG. 2.

The apparatus illustrated in FIGS. 2 to 4 may be manufactured such thatan evaporator 2 with a base plate having a plurality of parallel groovesin the second surface 22 is produced. This may be carried out byextrusion of aluminum, for instance.

A plurality of tubes 4 with internal longitudinal walls 5 can beproduced. The tubes 4 may be MPE (Multi Port Extruded) tubes which havebeen manufactured by extruding aluminum, for instance.

The hollow sections 8 and 9 can be produced in the selected end (or bothends) of the tubes 4 by first removing the internal walls 5 from the endof the tube. This can be done by milling with a water jet, for example.After this, the end can be plugged 30 by welding, for example, such thatfluid leakage from the hollow sections 8 and 9 to the outside can beavoided.

The tubes 4 are placed into the grooves in the evaporator 2 and attachedto the grooves by brazing, for instance. In case a manifold 27 is alsoproduced by drilling through the base plate of the evaporator 2 and theparts of the tubes 4 that penetrate into the evaporator 2, thenadditional attention should be paid during the brazing to ensure thatleak proof interfaces are obtained between the base plate 2 and thetubes 4. The plug 28 may then be welded to close the end of the manifold27.

FIGS. 5 to 8 illustrate a second exemplary embodiment of an apparatus.The embodiment of FIGS. 5 to 8 is very similar to the one explained inconnection with FIGS. 1 to 4. Therefore, the embodiment of FIGS. 5 to 8will be explained mainly by pointing out the differences between theseembodiments.

FIG. 5 illustrates the entire apparatus 21′, FIG. 5 is a partial crosssection illustrating the tubes 4′ and the elongated spacer elements 31between the tubes, and FIGS. 7 to 8 illustrate the tubes 4′ in moredetail.

In the second embodiment, the tubes 4′ extend through the evaporator 2′.In the illustrated example the evaporator 2′ includes a plurality ofelongated spacer elements 31 which are arranged between the tubes 4′ tokeep the tubes apart from each other. Therefore, the tubes 4′ partlypenetrate into the evaporator 2′ (are located between the spacers of theevaporator), and the channels located in these parts of the tubes 4′ areevaporator channels 6 that are embedded into the evaporator 2′, and theother channels of the tubes are condenser channels 7, located outside ofthe evaporator 2′.

Similarly, as in the previous embodiment, fins 26 can extend betweencondenser channels 7 of adjacent tubes 4′. Additionally, secondaryspacer elements 32 may be arranged between the condenser channels 7′ ofthe adjacent tubes at the lower edge of the tubes, as illustrated inFIG. 6.

The second embodiment utilizes an alternative way of implementing amanifold 27′. As best seen in FIG. 5, the manifold 27′ may be arrangedas an extension of the tubes 4′ to allow fluid flow via the manifoldbetween the hollow sections of the tubes 4′. The manifold 27′ may alsobe provided with a filling valve 29 providing access to the channels ofthe tubes 4′ from the outside of the apparatus 21′.

FIGS. 9 and 10 illustrate alternative tube designs. In the following, itis by way of example assumed that the tube design according to FIG. 9 isutilized in the second embodiment of the apparatus, as illustrated inFIGS. 5 to 8. However, as an alternative, it is possible to utilize thetube design of FIG. 10 in the second embodiment.

FIG. 9 illustrates the assembly of a tube 4′. A MPE (Multi PortExtruded) tube which has been manufactured by extruding aluminum, forinstance, is utilized as a wall element 33 between a pair of parallelplates 34. The MPE tube provides the tube 4′ with a plurality ofinternal longitudinal walls 5. These internal longitudinal walls dividethe tube 4′ into channels, of which some are evaporator channels 6 andsome condenser channels 7, as has been explained in connection with theembodiment of FIGS. 1 to 4.

The longitudinal length of the wall element 33 is shorter than thelongitudinal length of the plates 34, as best seen in FIG. 7. Thus,hollow sections 8 and 9 are formed at the opposite ends of the tube 4′,without any need to remove parts of the internal walls 5 (as forexample, in the first embodiment).

The plates 34 and the spacer elements 35 arranged between the plates 34along opposite first edges of the plates 34, together with plug elements30 (provided by attaching plates by welding, for example) arranged alongopposite second edges of the plates 34 together delimit a fluid tightspace within the tube 4′. However, naturally a hole for allowing fluidcommunication via the manifold 27′ may be provided in the tube 4′. Thedifferent parts of the tube 4′ may be soldered together, for example.

After production of a sufficient number of tubes 4′, spacer elements 31,secondary space elements 32 and fins 26 may be arranged between suchtubes in order to assemble the apparatus 2′ illustrated in FIGS. 5 to 8.The different parts of the apparatus 2′ may be soldered together.

The alternative tube design illustrated in FIG. 10 is very similar tothe one illustrated in FIG. 9. However, in FIG. 10 the wall element 33′used in the tube 4″ is not a MPE tube, but instead can be a corrugatedplate, for example. By shaping the plate into a suitable form thelongitudinal internal walls 5 of the pipe 4″ can be produced.

The spacers 35 and plug elements used in tube 4″ may be similar asexplained in connection with tube 4′, and the longitudinal length of thewall element 33′ is shorter than the longitudinal length of the plates34 in order to produce the hollow sections 8 and 9 at opposite ends ofthe tube 4″.

It is to be understood that the above description and the accompanyingfigures are only intended to illustrate exemplary embodiments of thepresent invention. It will be apparent to a person skilled in the artthat the invention can be varied and modified without departing from thescope of the invention.

Thus, it will be appreciated by those skilled in the art that thepresent invention can be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresently disclosed embodiments are therefore considered in all respectsto be illustrative and not restricted. The scope of the invention isindicated by the appended claims rather than the foregoing descriptionand all changes that come within the meaning and range and equivalencethereof are intended to be embraced therein.

1. An apparatus comprising: an evaporator with a first surface forreceiving a heat load from one or more electric components; tubes havinginternal longitudinal walls dividing the tubes into channels, whereinthe tubes partly penetrate into the evaporator for providing evaporatorchannels which are embedded into the evaporator, and condenser channelswhich are located outside of the evaporator; connecting parts at firstand second ends of the tubes for passing fluid from the evaporatorchannels into the condenser channels and for passing fluid from thecondenser channels into the evaporator channels, the connecting partshaving hollow sections located within the tubes, each hollow sectionconnecting the channels of a tube to each other in a vicinity of an endof the tube in order to allow fluid to flow between the channels of thetube via the hollow section; and fins extending between the condenserchannels of adjacent tubes.
 2. The apparatus according to claim 1,comprising: a manifold extending between the tubes for allowing fluid toflow between at least one channel of each tube via the manifold.
 3. Theapparatus according to claim 1, comprising: a manifold having a holeextending through the evaporator and parts of the tubes which penetrateinto the evaporator for allowing fluid to flow between evaporatorchannels of different tubes via the manifold.
 4. The apparatus accordingto claim 1, comprising: a manifold arranged as an extension of the tubesto allow fluid to flow via the manifold between the hollow sections ofthe tubes.
 5. The apparatus according to claim 1, comprising: at leastone filling valve providing access to at least one channel or manifoldof the apparatus for filling the at least one channel or manifold withfluid.
 6. The apparatus according to claim 1, wherein at least some ofthe channels comprise: capillary dimensions.
 7. The apparatus accordingto claim 1, wherein at least one of the tubes comprises: a pair ofplates with spacer elements arranged between the plates along oppositefirst edges of the plates, and with plug elements along the oppositesecond edges of the plates, wherein the spacer elements and the plugelements adjoin the plates to delimit a fluid tight space; and a wallelement arranged in the fluid tight space, the wall element having aplurality of internal walls which form longitudinal internal walls intothe tube, a longitudinal length of the wall element being shorter than alongitudinal length of the plates for forming hollow sections betweenthe plug elements and the wall element.
 8. The apparatus according toclaim 1, wherein the evaporator comprises: a plate with grooves intowhich the tubes are arranged for providing evaporator channels which areembedded into the evaporator.
 9. The apparatus according to claim 1,wherein the evaporator comprises: a plurality of elongated spacerelements arranged between the tubes, wherein the spacer elements and thetubes together form said first surface.
 10. The apparatus according toclaim 2, comprising: at least one filling valve providing access to atleast one channel or manifold of the apparatus for filling the at leastone channel or manifold with fluid.
 11. The apparatus according to claim10, wherein at least some of the channels comprise: capillarydimensions.
 12. The apparatus according to claim 11, wherein at leastone of the tubes comprises: a pair of plates with spacer elementsarranged between the plates along opposite first edges of the plates,and with plug elements along the opposite second edges of the plates,wherein the spacer elements and the plug elements adjoin the plates todelimit a fluid tight space; and a wall element arranged in the fluidtight space, the wall element having a plurality of internal walls whichform longitudinal internal walls into the tube, a longitudinal length ofthe wall element being shorter than a longitudinal length of the platesfor forming hollow sections between the plug elements and the wallelement.
 13. The apparatus according to claim 12, wherein the evaporatorcomprises: a plate with grooves into which the tubes are arranged forproviding evaporator channels which are embedded into the evaporator.14. The apparatus according to claim 12, wherein the evaporatorcomprises: a plurality of elongated spacer elements arranged between thetubes, wherein the spacer elements and the tubes together form saidfirst surface.